1. The Field of the Invention
The invention relates to a device and related method for detecting and measuring light output of an external light source (e.g., an LED dental curing light).
2. The Relevant Technology
In the field of dentistry, dental cavities are often filled and/or sealed with photosensitive compounds that are cured by exposure to radiant energy, such as visible light. These compounds, commonly referred to as light-curable compounds, are placed within dental cavity preparations or onto dental surfaces where they are subsequently irradiated by light. The radiated light causes photosensitive components within the compounds to polymerize, thereby hardening the light-curable compounds within the dental cavity preparation or another desired location.
Existing light-curing devices are typically configured with a light source, such as a quartz-tungsten-halogen (QTH) lamp bulb or an LED light source. QTH bulbs are particularly useful because they are configured to generate a broad spectrum of light that can be used to cure a broad range of products. In particular, a QTH bulb is typically configured to emit a continuous spectrum of light in a preferred range of about 350 nm to about 500 nm. Some QTH bulbs may even emit a broader spectrum of light, although filters are typically used to limit the range of emitted light to the preferred range mentioned above.
A broad light spectrum (e.g., that emitted by a QTH bulb) can be beneficial in that it allows curing of multiple types of materials. For example, camphorquinone is a common photo-initiator that is most responsive to blue light having a wavelength of about 455 nm to about 470 nm. Other light-curable products, however, including many adhesives are cured when they are irradiated by light wavelengths in the 350 nm to 400 nm range. Accordingly, QTH bulbs can be used to cure both camphorquinone initiated products as well as other adhesives.
Another problem with existing light-generating devices is that they are not very efficient. In particular, large quantities of radiation energy is lost due to filtering, dissipation, and light that is not properly directed into the patient's mouth. This is a problem because it generally results in increased power requirements for generating a desired output of radiation.
In an attempt to overcome problems of low efficiency and excess heat generation of QTH and other bulb light sources, some light-generating devices have been manufactured using alternative light generating sources, such as light-emitting diodes (LEDs) which are generally configured to only radiate light at specific wavelengths, thereby eliminating the need for special filters and generally reducing the amount of input power required to generate a desired output of radiation.
LEDs are particularly suitable light sources because they generate much less heat than QTH bulbs, thereby enabling the LEDs to be placed at the tip of the curing lights and to be inserted directly within the patient's mouth. This is particularly useful for reducing or eliminating the need for light guides such as optical fiber wands.
One limitation of LEDs, however, is that they are only configured to emit a narrow spectrum of light. For example, a 455 nm LED or LED array will generally only emit light having a spectrum of 455 nm±30 nm. Accordingly, a 455 nm LED light source will be well designed to cure camphorquinone initiated products, but will not be suitable for curing adhesives that are responsive to light in the 380 nm±30 nm range. Likewise, a 380 nm LED light source may be suitable to cure some adhesives, but will be unsuitable for curing camphorquinone initiated products. As a result, LED curing lights including a plurality of different LEDs have been developed to allow a single LED curing light to be used to cure both camphorquinone initiated products as well as other adhesives.
Because bulbs emit a wide spectrum, they are able to emit both visible and UV wavelengths simultaneously. This makes determining when a bulb has burned out simple, because it can be determined by a quick visual inspection. This is not the case with LED curing lights including a plurality of different LEDs (e.g., blue and UV). Because each LED emits a narrow spectrum of light, it takes two or more LEDs to emit both visible (e.g., blue) and UV wavelengths simultaneously. The condition of an LED emitting visible wavelengths of light (e.g., blue) is easily ascertained, but it can be very difficult to determine the condition of an LED that emits UV wavelengths of light. This makes it difficult to determine when a UV LED has burned out, as it cannot be determined by visual inspection.
In view of the foregoing, there exists a need for a device and method for determining the existence and intensity of light output by an LED curing light, particularly one including UV LEDs.